This invention relates to providing electrical connection between planar, essentially parallel, components.
In many electronic interconnect systems, it is necessary to provide electrical connection between essentially parallel surfaces of different components. These components can be at least two printed circuit boards representing different levels of interconnection in the system or can be a printed circuit board and some other type of component such as a display panel. As an example of the latter, ac plasma panel displays require electrical connection between glass covers and substrates and a printed circuit board so that the display can be appropriately addressed. In particular, a glass cover and glass substrate enclose a gas which is capable of being ionized when a bias is supplied to electrodes which are also formed on the substrate and cover. Contact pads are also protided on the facing surfaces of the substrate and cover, but outside the gas envelope, and are electrically connected to a printed circuit board which includes the necessary components for addressing the electrodes.
Several types of connectors have been proposed for providing electrical interconnection between parallel surfaces of a printed circuit board and another board or display component. These connectors are usually in the form of an elastomeric material consisting of alternating layers of conducting and nonconducting rubber (See, e.g., Connectors and Interconnection Handbook, Vol. 2, pp. 4-26 to 4-30 (Fort Washington Pa. Electronic Connector Study Groups, 1979)) or spring contacts (See, e.g., TKC Printed Circuit Connectors Catalog, Vol. 2, pp. 1-6, (Huntington Beach Calif., Ken Fleck Association, 1983)) which are placed between facing surfaces of the parallel components so as to interconnect corresponding contact pads. The parallel components and connectors are usually clamped together by screws running through holes in the components and a holder for the connector.
Such connectors are generally adequate for most applications. However, many problems exist, especially in the connection of plasma displays. For example, it is desirable to be able to provide a fairly stable connection between the cover, substrate and printed circuit board so that the device can be tested prior to actual clamping. Since the glass covers and substrates are fragile, some means is usually needed to prevent the clamping action from breaking these elements. It is also necessary in plasma displays to provide connection between the top of the substrate and the top of the printed circuit board (i.e. two non-facing surfaces).
Some connectors have been proposed to deal with some of the problems involved. For example, it has been proposed for LCD displays to provide a connector which includes a conductive member extending to the top surface of the display with an insulating support positioned on the opposite (bottom) surface of the display (See TKC Catalog cited above). Such a connector provides electrical contact from the top of the display to the printed wiring board. However, the contact force is apparently dependent upon the thickness of the display, and no provision is made for a padding element which would probably be required for use in conjunction with additional clamping which is desirable for a glass cover or substrate in a plasma display. It has also been proposed to provide electrical connection in a plasma display panel by means of a flexible circuit member extending between the glass and printed circuit board and mechanically attached thereto by spring clips on the edges of the glass and board (See, e.g., Bilsback et al. "Plasma Panel Display Presents Unique Packaging Problems," Electronic Packaging and Production, pp. 132-134 (March 1984)). Since the conductive element is a flex circuit, the distance between the glass and board must be fixed by some additional means. Also, padding elements which are not an integral part of the connector are required to prevent breakage of the glass and provide the appropriate contact force between tne conductive element and the glass or board.
It is, therefore, a primary object of the invention to provide an integral connector structure for making electrical contact between contact pads of different components with essentially parallel surfaces.